1. Field of the Invention
The present invention relates to a high-voltage power supply apparatus. More specifically, the present invention relates to a high-voltage power supply apparatus which controls supply voltages to two circuits respectively requiring voltages of different magnitudes which are both connected to an output winding of a single transformer.
2. Description of the Prior Art
Conventionally, equipment requiring a relatively high voltage and another voltage which is higher (hereinafter referred to as "medium voltage" and "high voltage"), for example, an electrostatic copier, electrostatic printer, electrostatic facsimile or the like is provided with two individual transformers dedicated to the medium voltage and the high voltage, respectively.
Such installation of the dedicated transformers in the respective circuit requiring the medium voltage (hereinafter referred to as "medium voltage circuit") and circuit requiring the high voltage (hereinafter referred to as "high voltage circuit") not only makes miniaturization of the power supply apparatus difficult but also raises the cost thereof. On the other hand, it is also possible for power to be supplied simultaneously to both the medium voltage circuit and the high voltage circuit using a common transformer. However, it is not easy to independently turn on and off the medium voltage circuit and the high voltage circuit in such a high-voltage power supply apparatus.